1：Experimental Design and Method Selection:

The study involved the design of an optical system with two prisms to expand the measurement region and improve the aspect ratio of measurable objects. The system uses a small-diameter optical fiber probe for precise measurements.

2：Sample Selection and Data Sources:

Measurements were conducted on a pin gauge with a diameter of 100 μm and a step height standard with a calibrated height of 189.6 nm to assess repeatability in the X-, Y-, and Z-directions.

3：6 nm to assess repeatability in the X-, Y-, and Z-directions. List of Experimental Equipment and Materials:

3. List of Experimental Equipment and Materials: The system includes a fine movement positioning XYZ piezo stage (P-562.3CD, Physik Instrument), a stylus with a shaft fabricated using an acid etching technique, and a tip fabricated by CO2 laser. Two laser diodes with a wavelength of 405 nm were used.

4：3CD, Physik Instrument), a stylus with a shaft fabricated using an acid etching technique, and a tip fabricated by CO2 laser. Two laser diodes with a wavelength of 405 nm were used. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The surface of the microstructure was scanned in the X-, Y-, and Z-directions using the piezo stage. The contact between the stylus tip and the measured surface was detected using a laser-based non-contact method.

5：Data Analysis Methods:

The repeatability of measurements was assessed by calculating the standard deviation of the point measurements and the diameter of the pin gauge. The step height was calculated by measuring the distance between the least square fitted straight lines of the upper and lower surfaces.